8.1.3 Preprocessor Options

Following command line options control the preprocessor feature. See Preprocessor, for a detailed discussion of these.

--no-preprocessor

Do not run the preprocessor.

--preprocessor[=command]

If command is supplied, use it as the external preprocessor instead of the default. This overrides the preprocessor.command setting (see conf-preprocessor).

If used without arguments, forces the use of the configured preprocessor. This form is intended as a way to manually enable the use of the preprocessor if disabled in the configuration.

-D name[=value]

--define=name[=value]

Define a preprocessor symbol name to have a value value. This option is ignored if the preprocessor.pass-defines configuration setting is false.

-U name

--undefine=name

Undefine the preprocessor symbol name. This option is ignored if the preprocessor.pass-defines configuration setting is false.

-E

Stop after the preprocessing stage; do not run the compiler proper. The output is in the form of preprocessed source code, which is sent to the standard output.